public abstract class Visitor
{
	public abstract void visit(Nod n);
	public void visit(Frunza f)
	{
		System.out.print(f.toString());
	}
	public void visit(NodAbstract n)
	{
		if(n instanceof Nod)
			visit((Nod)n);
		else if(n instanceof Frunza)
			visit((Frunza)n);
	}
}